Add explicit health endpoint

- Define @Bean for Health endpoint in ParentConfiguration (XD global beans)
  with @ConditionalOnExpression("${endpoints.health.enabled:true}")
 - Added VanillaHealthIndicator for the health endpoint
instead of the SimpleHealthIndicator which uses dataSource
XD-1437 Exclude slf4j Transitive Dependencies

Force all slf4j dependencies to project version.
Remove json related modules

Add options to script module
Fix basic_stream_tests

- Replace json-field-value-extractor processor with splitter that uses
XD-1378: Add metadata to Splunk module
Fix tweet tests.

Use hyphenated module name 'aggregate-counter' and correct option.
XD-1435 Update Executions Page

- Added job name, instanceId along with the conditional check to show
restart action button only if the job execution is restartable.
- Fixed the JobExecution list to refresh the list upon restart action
XD-1436 Miscellaneous cleanup in UI

- Fix subtitle text on each tab in Jobs page that would vary based on
the tab selected.
- Fix job name display in Job launch page
- Style fix for batch job and subtitle so that avoids empty lines
occupying the prime view
XD-1418 XD-1419 XD-1420 - Add support for machine learning

These three issues are

 - XD-1418 - Create subproject spring-xd-analytics-ml.
 - XD-1419 - Create subproject spring-xd-analytics-ml-pmml.
 - XD-1420 - Create a JPMML module that will evaluate a model.

The project spring-xd-analytics-ml adds basic support for advanced analytics by providing the necessary infrastructure to be able to define analytic stream processors by introducing a new module

The project spring-xd-analytics-ml-pmml adds support for evaluation of PMML models from an analytic stream processor

The module XML defintion is located in modules/processor/analytic-pmml/

Additional Javadoc and reference documentation will come in a seperate commit
XD-1451 - Support CI build in Travis
XD-944 Cleanup JSON mapping class

- Remove TypedJsonMapper and its tests
- This also removes TypedJsonMapper$SmartJsonConversionException class
Add rabbit & redis to travis build
XD-1170 Updated the splunk adapter to M2

The M1 version did not work because a class was moved to a different package.
Gary released the M2 yesterday.
Moved libs-snapshot to the top of the repo list.
XD-1439: Prevent module context leak

Please refer to  https://jira.spring.io/browse/XD-1443
XD-1441: WIP
XD-1441: Implement XD_MODULE_CONFIG_x